Pulse jet engine



April 13, 1965 R, B. BLACK 3,177,663

PULSE JET ENGINE N INVENTOR ROBERT B. BLACK MTM@ ATTORNEYS April 13,1965 R. B. BLACK 3,177,353

PULSE JET ENGINE Filed July 12, 1962 y 2 sheets-sheet 2 47 @5. Jl 3 J030 INVENTOR G ROBERT B. BLACK United States Patent p 3,177,663 p PULSEJET ENGINE Y Robert ll. Black, 125 Southern St., Corpus Christi, Tex.Filed July 12, 1962, Ser. No. 299,343 Claims. (Cl. 61E-39.77)

The present invention deals 'broadly with an internal combustionapparatus and more specically with a pulse type combustion gasgenerating device adapted either for producing power or for deliveringproducts of combustion for transmission to a point of use.

Pulse jet engines have been very commonly used for generating power, buthave presented many serious limitations because of their normally closedinlet ilaps valves. Such engines also require a comparatively longexhaust or tail pipe to create the resonance forces necessary foraspiration and `ignition of the fuel-air mixture. The long exhaust ortail pipe is necessary since this creates an inertial gas column andcontines the exhaust in order that there be a residual flame whichignites the incoming combustible gas in the engine.` Also, these enginescannot discharge against back pressure aside from that nominal amount inthe open ended tail pipe which holds the residual flame in readiness toignite the next combustible charge delivered into the cylinder. Theoutward flow of the inertial gas column creates a partial vacuum whichopens the normally closed valves for inlet of air to mix with the fueland be ignited by the residual iiame when the proper combustible mixtureis attained. It was a recognition of these shortcomings of the pulse jetengines and the need of a construction which would operate at all timesona back pressure far greater than that created by the pulse jet enginetail pipe, which led to the conception and development of the presentinvention.

Accordingly, among the objects of the present invention is the provisionof a pulse type engine which does not use normally closed inlet valveswhich open only when the pressure inside the engine is less than thatoutside, but rather uses normally open valves which remain open evenwhenthe pressure inside the engine is moderately greater than on theoutside.

Another object of the invention is to utilize the delivery of fuel undermoderately high pressure to draw air into the inlet end of the assemblywhere it mixes with the fuel on the way to the combustion chamber.

Another object of the invention is to provide an engine which isself-starting without the use of compressed air or other startingauxiliaries.

Another object is to have not only normally open intake valves ahead ofthe combustion chamber, but also normally open breather valves,immediately following the combustion chamber so as to make aspirationand combustion possible with the use of a very minimum of energy.

A further object is to provide a pulse or intermittent type enginehaving the ability to discharge combustion gasses against moderatelyhigh back pressure thus making the engine practical for manyapplications where the ordinary pulse jet engine would be useless.

A further object of this invention is to eliminate dependence uponresidual flame for ignition of the combustible mixture, which`dependence is essential to the ordinary pulse jet engine, and tosubstitute therefor an electrical spark ignition which may be continuousor timed, and in this way to provide for better, more cornpletecombustion cycles, and at the same time to make possible phasedoperation of multiple units.

A still further object is to produce a very compact engine of Vthis typewhich eliminates the comparatively long tail pipe heretofore required inorder to create the essential resonance forcesnecessary for aspirationand ignition of the fuel-air mixture.

frice Still further objects and advantages of the invention will appearas the description proceeds.

I have illustrated my invention in preferred form in the accompanyingdrawings wherein FIGURE 1 is an elevational view with part of the coversof the valve assemblies broken away to show the petal valves in fullline in circular recesses.

FIGURE 2 is a longitudinal section taken as indicated by line 2-2 ofFIGURE 3.

FIGURE 3 is a fragmentary plan view with the top cover of the inletvalve assembly removed.

FIGURE 4 is taken on the line 4-4 of FIGURE 1 and is a plan section ofthe inlet valve housing with the covers and petal valves omitted.

FIGURE 5 is an enlarged cross-section taken on the line S-S of FIGURE 1.

FIGURE 6 is a cross-section on the same scale as FIGURE 5 taken on theline 6*-6 of FIGURE 1 with the covers and petal valves omitted.

FIGURE 7 is a cross-section through a check valve which may be used ifthe combustion unit is to be used for compressing gases.

FIGURE 8 is a wiring diagram for the ignition system of the combustionunit. p

FIGURE 9 is a modified form of ignition for the combustion unit, and

FIGURE 10 is a fragmentary cross-section of a modified constructiontaken substantially at the same point on FIGURE 1 as is shown in FIGURE5.

Referring now particularly to FIGURES 1 and 2 of the drawings, thecombustion chamber, indicated by reference numeral 11, is connected toan inlet valve assembly or aspiration chamber 12 by` throat 13. At theopposite end, the combustion chamber 11 is connected by outlet throat 14to a breather valve chamber or assembly 1S. The aspiration chamber has abody member 16 which is provided with acylindrical bore 17 lengthwise ofthe same, with such bore being internally threaded at opposite ends.Inside the bore 17 are mounted tubular frustreconical throat inserts 1S,19, and 20 connected together co-axially and mounted on the side Wallsof the cylindrical bore 17 of the body member 16 by means of elongatedsupport members 21.

The outer end of the cyindrical bore is closed by a plug 22 which isthreaded into theend of the bore. A nut 23 is threaded into the centerof the plug 22 and a nut 24 is threaded into nut 23 with the two nutsbeing co-axially bored and actingas a packing gland toA adjustablygripfeed inlet tube 25 which carries a nozzle 26 on the end thereof fordischarging fuel under pressure coaxially into the throat inserts 18,19, and 2i) within the bore 17 thereby creating a partial vacuum in theaspiration chamber.

It is to be noted in this connection that the packing gland assembly ofthe nuts 23 and 24 permits adjush vment of the location of nozzle 26over a. range of positions relative to throat insert 18 to facilitatethe best positioning of the nozzle 26 for creation of the maximumsuction effect through the throat inserts.

Body member 16is formed with cross-bores 27 both vertically andcrosswise as seen in FIGURES 2, 5, and 6 to provide air inlet openingsinto the cylindrical bore 17 Body member 16 is also provided withcounter-bores 28 on its four faces which are covered by means of coverplates 29 having inlet ports 30 in alignment with the cross-bores'27 inbody member-.16. These inlet ports 30 are preferably a little smallerthan the diameter of the cross-bores 27 for purposes to be hereinafter`ex- Mounted inside the counter-'bores 28 on the and uncover the inletports 30. These reed valves are of petal shape and are normally open,i.e., in the position in which the inlet ports 30 are uncovered. Theyare of low inertia type and are ground and polished to seat accuratelyand provide a tight seal against escape of gases through the inlet portsduring the pressure phase of the combustion cycle. These reed valveshave a central portion 46 and radially extending individual outer petalshaped portions 47 adapted to overlie and cover the inlet ports 30. Thecentral portion 46 of each of the valve members is secured in positionon the cover plates 29 of the valve assemblies by means of a bolt 48.The cover plates 29 may be secured in place on the body member 16 in anyconvenient manner as by means of cap screws 32.

The end of body member 16 opposed to that of plug 22 is in threadedengagement with inlet throat 13 of the combustion chamber 11, such inletthroat portion providing a cone shaped passage between the aspirationchamber and the combustion chamber with the small end of the passagefreely receiving the small end of throat insert and the larger endopening into the combustion chamber 11. This combustion chamber has aboss 33 into which is threaded a spark plug 34 with the points 3Sextending inside the combustion chamber 11 in position to ignite acombustible mixture when the same is admitted through the inlet throatportion 13 of the combustion chamber 11.

The outlet throat 14 of the combustion chamber has a threaded connectionwith an outlet or breather valve assembly 15 and the outlet end 36 ofthe breather valve provides an exhaust port or opening from the breathervalve assembly which is threaded to permit connection thereof to a line37 leading to a point of use of the products of combustion of chamber11. The outlet or breather valve assembly 15 is substantially the sameas inlet valve assembly 12 except that it is open ended and does nothave throat inserts. The reed valves 3S of the breather valve assemblyare substantially the same as the reed valves 31 of the inlet valveassembly 12 and are mounted to cover and uncover exhaust opening 30 inthe cover plates of the breather valve assembly (parts in the breathervalve assembly which are similar to those in the aspiration valveassembly have prime numbers added).

The power unit above described can operate on a continuous sparkdelivered from spark coil 39 as shown in FIGURE 8 and is also adaptedfor operation on a timed spark delivered through a spark timer 40 asillustrated in FIGURE 9.

The operation of the engine is as follows:

Gaseous fuel such as propane is led to the nozzle 26 through the fuelline at a pressure of approximately 125 p.s.i. The fuel is dischargedfrom the nozzle into the conical throat inserts and as it passes throughthese throat inserts it creates a partial vacuum and thereby entrainscombustion air through the open valve controlled inlet ports which allowthe air to enter the aspiration chamber with a minimum resistance. Thecombustion chamber is quickly filled with a fuel-air mixture at thecorrect ratio for eflicient combustion. The fuel-air mixture in thecombustion chamber 11 is ignited by the spark of spark plug 34. When thefuelair mixture is ignited by the spark plug the combustion results in asubstantial and very sudden increase in pressure which immediatelycloses all of the reed valves in both the aspirationY chamber and thebreather valve assembly. The hot combustion gases thus created have noplace to escape but through the exhaust outlet 36 of the breather valvewhere they pass at a pressure of 90-110 p.s.i. and may be utilized to douseful work.

It has been found that the best performance obtained is by timedignition in which case the combustible mixture is fired at the precisepoint when the combustion chamber and breather valve chamber arecompletely l filled. Another advantage of the timed ignition is that anynumber of these combustion units may be used together and kept inperfect phase with one another by a small synchronizer.

To summarize, the combustion unit above described operates on a threephase cycle, i.e.

(l) Aspiration phase.-Fuelair mixture is forced into the combustionchamber.

(2) Combustion phaser-The fuel-air mixture is ignited and the hotexpanded gases are forced from a discharge port to do useful work.During this phase all of the reed valves instantly close.

(3) Exhaust phase-When the pressure has been dissipated thespring-loaded, normally open reed Valves instantly open allowing theburned gases to escape from the breather valve assembly as the freshfuel-air mixture is admitted to the combustion chamber through theaspiration chamber.

It will be noted that the aspiration phase and the exhaust phase occursimultaneously, the aspiration action scavenging the burned gases fromthe previous cycle. As Twas pointed out above, the spark ignition mightbe continuous in which case the fuel-air mixture will re when a criticalratio is reached in the area of the spark plug. In this case, cyclefrequency is determined by the rate at which the fresh fuel-air mixtureis supplied to fill the chamber after each combustion cycle. v

In certain instances it is advantageous to time the fuel admission,inasmuch as continuous admission mayresult in some loss of thecombustible mixture through the exhaust openings in the breather valvechamber prior to the combustion cycle. In such system, fresh fuel-airmixture should enter the combustion chamber only until the combustionchamber and breather valve chamber are completely filled. The fuel Howshould then be terminated and the mixture fired, m

Continuous fuel admission may be employed efficiently if the correctignition frequency is used. In this case the fuel-air mixture will beiired at the precise interval required to rell the combustion unit withfresh fuel-air charge which scavenges the burned gases from the previouscycle.

If the combustion unit is to be used for compressing gas, a check valveas shown in FIGURE 7 is employed. This valve is located at the outletport 36 of the breather valve assembly 15. This valve consists of valvemember 41 which seats against valve seat 42. The valve stern 43 holdsthe valve in alignment with the valve seat and spring 44 and keeps thevalve in normally closed position. When the combustion phaseV of thecycle takes place, the pressure of the hot combustion gases opens thespring-loaded valve 41 allowing the gases to escape through outlet port45. This port may lead to a pressure tank for storage of the exhaustgases prior to use for paints, spray guns or other purposes requiringcompressed gases.

The reed valve assemblies are shown in more detail in FIGURES 2 and 5.Referring to FIGURE 5, it is pointed out that when combustion takesplace, the hot gases at high pressure back up through cylindrical bore17 and the cross-bores 27 of the aspiration chamber in line with theinlet ports 30. The expanding gases act against the under face of thepetal valves and since the inlet ports 30 are a little smaller than thecross-bores, this back pressure in the cross-bores will assure theinstant closing of the petal valves to cover the inlet ports. The sameaction takes place in the breather chamber when combustion occurs in thecombustion chamber.

In FIGURE l0 I have illustrated my invention as applied to an enginehaving a cylindrically shaped aspiraation valve assembly. (Like parts inthis figure to those in FIGURE 5 have double prime marks added.) In thisfigure the aspiration chamber 12 is circular in crosssection. The bodyof the aspiration chamber has a cylindrical bore 17, throat inserts 18,and 19 and 20 as shown in FIGURES 2, 4, 5, and 6 supported by throatinsert supports 21". Cross-bores 27" extend radially from cylindricalbore 1'7" and lead to openings 30 in the cylindrical cover of theaspiration chamber. Reed valves 31 are bolted to the interior of thecylindrical cover and are adapted to cover and uncover the inletopenings. As in the other ligures, these valves will close instantlyywhen back pressure from the combustion chamber i is transmitted throughcross-bores 27 to the under faces of the valves. The breather valveassembly can also be of cylindrical form, but, of course, the throatinserts would be omitted. i

The use of a breatherV valve assembly as shown in the drawings withspark plug ignition of the fuel-air mixture gases completely eliminatesneed for a long tail pipe and permits operation of the engine against amuch higher back pressure than is possible with the usual type of pulsejet engines.

I claim as my invention:

1. A pulse jet engine having a combustion chamber and an aspirationchamber and breather chamber communicating therewith a plurality of airinlet openings formed in the walls of said aspiration chamber, aplurality of reed valves supported to cover and uncover said openings,said reed valves being normally open; means to introduce fuel underpressure through said aspiration chamber thereby lowering the internalpressure in said chamber and drawing combustion air through saidopenings, means in said combustion chamber to ignite the fuel-airmixture therein, an outlet port in said breather chamber, a plurality ofexhaust openings in the walls of said breather chamber, a plurality ofreed valves supported to cover and uncover said exhaust openings, saidreed valves being normally open, the reed valves in the aspirationchamber and the breather chamber being constructed and arranged to beclosed by pressure of the expanded gases on explosion of the fuel-airmixture in the combustion chamber.

2. A pulse jet engine having a combustion chamber and an aspirationchamber and breather chamber communicating therewith a plurality of airinlet openings formed in the walls of said aspiration chamber, aplurality of reed valves supported to cover and uncover said openings,said reed valves being normally open; a throat connecting saidaspiration chamber and combustion chamber, frustro conical tubularmembers mounted in said aspiration chamber to discharge into said throatco-axially thereof, means to introduce fuel under pressure into saidtubular members coaxially thereof, thereby drawing combustion airthrough said openings, means in said combustion charnber to ignite thefuel-air mixture therein, an outlet port in said breather chamber, aplurality of exhaust openings in the walls of said breather chamber, aplurality of reed valves supported to cover and uncover said exhaustopenings, said reed Valves being normally open, the reed valves in theaspiration chamber and the breather charnber being constructed andarranged to be closed by pressure of the expanded gases on explosion ofthe fuel-air mixture in the combustion chamber.

3. A construction according to claim 1 wherein the aspiration chamberhas a housing having a central cylindrical bore, a throat connectingsaid bore to the combustion chamber, means to discharge fuel underpressure into said cylindrical bore, a plurality cross bores in saidhousing connecting said central bore and the air inlet openings in thewallsof the chamber, the normally open reed valves being interposedbetween the ends of said cross bores and said air inlets.

4. A construction according to claim l wherein the breather chamber hasa housing having a central cylindrical bore with the outlet port at theend thereof, a throat connecting said bore to the combustion` chamber, apluralf ity of cross bores in said housing connecting said central boreand the exhaust openings in the walls of the chamber,the normally openreed valves being interposed be- 6 tween the ends of said cross boresand said exhaust openings.

. 5. A construction according to claim 1 wherein the ignitionV meanscomprises` an intermittently operating spark plug.

6. A construction according to claim 2 wherein the aspiration chamberhas a housing having a central cylindri` cal bore, said throatconnecting said bore to the combustion chamber, the frustro conicaltubular members being mounted co-axially in said cylindrical bore, and aplurality of cross bores in said housing connecting said central boreand the air inlet openings in the walls of the chamber, the normallyopen reed valves being interposed between the ends of said cross boresand said air inlet openings.

7. A construction according to claim 2 wherein the aspiration chamberhas a housing having a central cylindrical bore having said frustroconical members mounted therein, a throat connecting said bore to 'thecombustion chamber, a plurality of cross bores in said housingconnecting said central bore and the air inlet openings iu the walls ofthe chamber, the normally open reed valves being interposed between theends of said cross bores and said air inlets.

8. A construction according to claim 2 wherein the breather chamber hasa housing having a central cylindrical bore with the outlet port at theend thereof, a throat connecting said bore to the combustion chamber, aplurality of cross bores in said housing connecting said central boreand the exhaust openings in the walls of the chamber, the normally openreed valves being interposed oetween the ends of said cross bores andsaid exhaust openings.

9. A construction according to claim 2 wherein the ignition meanscomprises an intermittently operating spark plug.

10. A pulse jet engine having a combustion chamber and an aspirationchamber communicating therewith, said aspiration chamber having ahousing having a central cylindrical bore and a plurality of air inletopenings formed in the walls thereof, a plurality of cross bores in thehousing connecting said central bore and the air inlet openings, aplurality of reed valves interposed between the ends of said cross boresand the air inlet: openings, said reed valves being supported to coverand uncover said air inlet openings and being in normally open position,means to introduce fuel under pressure into said cylindrical borethereby lowering the internal pressure in said chamber and drawingcombustion air through said openings, means in said combustion chamberto ignite the fuel-air mixture therein, the said reed valves beingconstructed and arranged to be closed by the expanded gases on explosionof the fuel-air mixture in the combustion chamber.

11. A construction according to claim 10 wherein the fuel under pressureis discharged into a plurality of frustro conical tubular membersmounted in said central tubular bore co-axially therewith.

12. A construction according to claim 10 wherein the ignition meanscomprises an intermittently operating sparkplug.

13. A pulse jet engine having a combustion chamber, means to inject afuel air mixture into said combustion chamber and means in said chamberto ignite the fuelair mixture therein, a breather valve chambercommunicating with said combustion chamber, an outlet port in said valvechamber, a plurality of exhaust openings formed in the walls of saidvalve chamber, a plurality of reed valves adapted to cover and uncoversaid exhaust openings, said reed valves being in normally open positionand being constructed and arranged to be closed by pressure of theexpanded gases on explosion of the fuel-air mixture in the combustionchamber.

14. A construction according to claim i3 wherein said breather valvechamber has a housing with a central bore therein communicating with'thecombustion chamber and a plurality of cross bores leading from saidcentral bore to the exhaust openings, the said reed valvesbeinginterposed between the ends of said cross bores and the exhaustopenings.

15.` A construction according to claim 13 wherein said breather valvechamber has a housing having a central bore therein communicating withthe combustion chamberja plurality of cross bores leading from saidcentral bore to the exhaust'openings, the said reed valves beinginterposed between the ends of said cross bores and the exhaustopenings, and a normally closedvalve member covering said outlet port,said valve member being constructed and arranged to be Opened by thepressure of the expanded gases on explosion of the fuel-air mixture inthe combustion chamber.

References Cited bythe Examiner Y UNITED STATES PATENTS SAMUEL LEVINE,Primary Examiner.

ABRAM BLUM, Examiner.

1. A PULSE JET ENGINE HAVING A COMBUSTION CHAMBER AND AN ASPIRATIONCHAMBER AND BREATHER CHAMBER COMMUNICATING THEREWITH A PLURALITY OF AIRINLET OPENINGS FORMED IN THE WALLS OF SAID ASPIRATION CHAMBER, APLURALITY OF REED VALVES SUPPORTED TO COVER AND UNCOVER SAID OPENINGS,SAID REED VALVES BEING NORMALLY OPEN; MEANS TO INTRODUCE FUEL UNDERPRESSURE THROUGH SAID ASPIRATION CHAMBER THEREBY LOWERING THE INTERNALPRESSURE IN SAID CHAMBER AND DRAWING COMBUSTION AIR THROUGH SAIDOPENINGS, MEANS IN SAID COMBUSTION CHAMBER TO IGNITE THE FUEL-AIRMIXTURE THEREIN, AN OUTLET PORT IN SAID BREATHER CHAMBER, A PLURALITY OFEXHAUST OPENINGS IN THE WALLS OF SAID BREATHER CHAMBER, A PLURALITY OFREED VALVES SUPPORTED TO COVER AND UNCOVER SAID EXHAUST OPENINGS, SAIDREED VALVES BEING NORMALLY OPEN, THE REED VALVES IN THE ASPIRATIONCHAMBER AND THE BREATHER CHAMBER BEING CONSTRUCTED AND ARRANGED TO BECLOSED BY PRESSURE OF THE EXPANDED GASES ON EXPLOSION OF THE FUEL-AIRMIXTURE IN THE COMBUSTION CHAMBER.